Spectrophotometers have been available for a considerable number of years, and have been used to analyze the composition of various types of materials, including gases, liquids and the like. This is based on the fact that different chemical compositions absorb energy at different frequencies, so that by varying the frequency of the energy as it passes through the sample, the spectrophotometer output can identify which energy frequencies were absorbed by the sample and which were not. Thus, the chemicals present in the sample can be readily identified.
The spectrophotometer also can identify the amount of energy absorbed by the sample at each given frequency. Thus, the quantity of each chemical present in the chemical composition can be determined.
Such analysis can be performed with any one of various different ranges of energy such as infrared, ultraviolet and the like, each of which pertains to a separate range of frequencies.
Prior absorption cells for holding the sample through which the energy is passed have been capable of performing the aforedescribed analysis in conjunction with suitable spectrophotometric equipment. However, such prior cells have not been particularly sensitive in providing both quantitative and qualitative analyses. That is, prior cells have been so constructed that only a very small portion of the sample has received the energy from the spectrophotometric equipment and, as such, the sensitivity has been very minimal.
It has long been realized that to increase such sensitivity, it is desirable to pass the energy through a very large percentage of the available sample, but such prior devices have not been constructed to enable this to take place.
The present invention, on the other hand, provides a gas-absorption cell having, within the sample enclosure, a continuous reflective surface, such as a circular surface, reflecting energy back and forth, through a sample within the enclosure. By initially directing such energy flow at a predetermined angle within the enclosure, the back-and-forth reflections are caused to progress about the surface to thereby contact a substantially greater amount of the sample than could be contacted by a single pass through the sample.